We doubted our 45-minute WMD claim, admits Beckett

Margaret Beckett said the claim had not been repeated in Commons debates before the 2003 invasion of Iraq because it was already deemed "irrelevant"

Margaret Beckett has admitted the Government realised before the Iraq war that its 45-minute claim about Saddam Hussein's weapons may have been wrong.

The Foreign Secretary said the claim had not been repeated in Commons debates before the 2003 invasion of Iraq because it was already deemed "irrelevant" and people were wondering if it was really true.

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In the 2002 Downing Street dossier making the case for war, Tony Blair had written that Saddam could have WMDs ready for use within 45 minutes of an order being given.

Today Mrs Beckett said: "That was a statement that was made once and it was thought to be of such little relevance — and perhaps people began quickly to say, I'm not sure about that' — that it was never used once in all the debates in the House of Commons."

Her words imply Mr Blair and ministers quietly dropped the allegation yet failed to withdraw it or correct the record. After speaking on BBC Radio 4's Today show Mrs Beckett was challenged by presenter John Humphrys on why the claim had not been corrected in public.

She retorted: "Oh, come on — nobody thought it was relevant. Nobody thought it was a big sweeping statement."

In fact, the 45-minute claim was at the heart of the Downing Street dossier issued in September 2002.

Writing in the foreword to the dossier, Mr Blair said: "The document discloses that his military planning allows for some of the WMD to be ready within 45 minutes of an order to use them."

The claim was repeated four times in the dossier and cited in at least one speech by Mr Blair to see off a Commons rebellion.

It was also central to the bitter row over whether the dossier was "sexed up" which led to the death of Ministry of Defence weapons scientist David Kelly in July 2003.

After the failure to discover any WMD in Iraq following the invasion, the BBC reported the claim had been inserted at the behest of spin doctor Alastair Campbell.

His fight to clear his name fuelled the row that led to Dr Kelly's suicide and the Hutton inquiry, which discovered the claim was based on secondhand information and related to battlefield munitions rather than strategic weapons.

The 2004 Butler report found the source of the information was not safe, but the Government did not announce until October 2004 that intelligence services had withdrawn the claim.

No 10 referred questions about Mrs Beckett's comments to the Foreign Office, where a spokesman said: "That whole episode has been endlessly picked over and we have nothing to add to the conclusions of Lord Hutton and Lord Butler."

Shadow foreign secretary William Hague said: "If it is true that the 45-minute claim had been discounted before the invasion, it is appalling that there seems to have been no co-ordination between the ministers to put the record straight.

Mrs Beckett's comments came after the outgoing head of the respected Chatham House think tank issued a damning report into the Iraq invasion. Branding the war "a terrible mistake", Victor Bulmer-Thomas said it had damaged Britain's influence abroad.

The report added that Mr Blair had been unable to influence the Bush administration in "any significant way".

In an angry riposte Mrs Beckett called the paper "threadbare". She said it was "flawed" and "ridiculously wrong" to claim Mr Blair exerted no influence in Washington.

Former foreign office minister Denis MacShane, a member of Chatham House's council, said the report was a personal statement and had not been discussed by the council.